The present invention relates to an interworking unit for use on a broadband campus network which will interconnect the broadband network with a narrowband PABX. The unit will provide conversion between the cell based switching of the broadband network and the 64 Kbit circuit switching of the narrowband PABX. In order to enable the broadband users to have access to the normal PABX style telephony facilities, the interworking unit will adapt the broadband signalling to narrowband signalling.
A basic block diagram of a typical system is shown in FIG. 1.